Quality assessment of tumor marker determinations: a proposal for a supraregional scheme.

The use of tumor marker tests has increased progressively in the last decade concomitant with the advent of new monoclonal antibodies and their growing use in clinical oncology for various follow-up programs. External quality assessment (EQA) schemes widely adopted in clinical chemistry, have been extended in the last decade to immunoassays of hormones and tumor markers. EQA results can provide realistic information on the quality of the assays, performed under routine conditions.

Expression of ras oncogene p21 protein in normal and neoplastic ovarian tissues: correlation with histopathologic features and receptors for estrogen, progesterone, and epidermal growth factor.

Objective: The aim of the study was to investigate the biologic significance of p21 expression in normal and neoplastic ovarian tissues.

Study Design: Western blotting analysis of p21/ras oncoprotein was conducted in a group of 14 normal and cystic ovaries, six benign tumors, 42 primary ovarian cancers, and 15 omental metastases.

Results: Levels of p21 were similar in normal and cystic ovaries and in benign tumors, whereas they were significantly higher in malignant tumors than in control tissues (median 1.